The beneficial properties of fluoroelastomers are well known in the art and include for example, high temperature resistance, high chemical resistance including for example high resistance to solvents, fuels and corrosive chemicals and non-flammability. Because of these beneficial properties, fluoroelastomers find wide application particularly where materials are exposed to high temperature and/or chemicals.
For example, fluoroelastomers are used in fuel management systems which include for example fuel storage components, such as a fuel tank, fuel pump couplers, filler neckhoses, fuel tank cap seal and the like; fuel delivery components, such as fuel line hoses and tubings, fuel filler lines, fuel supply lines and in particular high temperature fuel lines in cars or other motor vehicles because of their excellent resistance to fuels and because of the good barrier properties that can be achieved with fluoroelastomers.
The fluoropolymers, which upon curing yield the fluoroelastomers are generally more expensive than non-fluorine polymers and accordingly, materials have been developed in which the fluoropolymer is used in combination with other materials to reduce the overall cost. For example, it has been proposed to use a relatively thin layer of fluoroelastomer as an inner layer of a multilayer hose where the outerlayer of the hose is then a non-fluorine elastomer. For example U.S. Pat. No. 6,106,914 relates to a hose, having a laminate structure, comprising of a first layer formed of a fluoro rubber or a fluoro resin and as second layer formed of an epichlorohydrin. U.S. Pat. No. 6,340,511 relates to a fuel hose comprising an inner layer of fluoroelastomer and an outer layer formed from a blend of polyvinyl chloride (PVC) and acrylonitrile butadiene rubber (NBR) that are adhered well by vulcanisation.
In recent years, increased environmental concerns have led to the development of low emission diesel fuel, i.e. diesel fuel of biological origin, comprising vegetable oil methyl ester. At severe conditions, i.e. high temperature and humidity, hydrolysis products can be formed that will accelerate swelling and deterioration of the currently used fuel management systems. A need exists for a fuel management system having improved barrier properties. Accordingly, it would be desirable to find a way of improving the resistance of a fluoroelastomer layer, used in fuel management systems, when brought in contact with diesel fuel, more in particular with diesel fuel of biological origin.